THEORY OF STATISTICS. 
ADDITIONAL REFERENCES. 
History of Official Statistics (p. 6). 
(1) Koren, J. (edited by), The History of Statistics, their Development and 
Progress in many Countries, New York, The Macmillan Co., 1918. 
(A collection of articles, mainly on the progress of official statistics, 
written by a specialist for each country.) 
Contingency (p. 73). 
(2) PrarsoN, KARL, “On the Measurement of the Influence of Broad 
Categories on Correlation,” Biometrika, vol. ix., 1913, p. 116. 
(3) PEARSON, KARL, “On the General Theory of Multiple Contingency with 
Special Reference to Partial Contingency,” Biometrika, vol. xi., 1916, 
P. 145. (An extension of the method of contingency coefficients to 
classification subjected to various conditions; arithmetical examples 
are provided in the undermentioned paper.) 
(4) PEARSON, KARL, and J. F. TocHER, “ On Criteria for the Existence of 
Differential Death-Rates,” Biometrika, vol. xi., 1916, p. 159. 
(5) RrrcHIE-ScorT, A., “The Correlation Coefficient of a Polychoric Table,” 
Biometrika, vol. xii., 1918, p. 93. (Considers various methods of 
measuring association with special reference to 4 x 3-fold classificatious.) 
(6) PEARsoN, KARL, and E. 8. PEArsoN, On Polychoric Coefficients of 
Correlation,” Biometrika, vol. xiv., 1922, p. 127. 
The Mode (p. 130). 
(7) DoobsoN, ARTHUR T., “Relation of the Mode, Median and Mean, in 
Frequency Curves,” Biometrika, vol. xi., 1916-17, p. 429. (Gives a 
proof of the relation noted on p. 121.) 
Index-numbers (p. 130). 
There are useful discussions as to method in the following :— 
(8) KniBs, G. H., ‘“ Prices, Price-Indexes, and Cost of Living in Australia,” 
Commonwealth of Australia, Labowr and Industrial Branch, Report 
No. 1, 1912. 
(9) Woop, Frances, ‘‘ The Course of Real Wages in London, 1900-12,” 
Jour. Roy. Stat. Soc., vol. 1xxvii., 1918-14, p. 1. 
(10) WorkiNG Crasses, Cost oF LiviNe COMMITTEE, 1918, Report (Cd. 
8980, 1918), H.M. Stationery Office. 
(11) BowLEY, A. L., ‘“ The Measurement of Changes in Cost of Living,” 
Jour. Roy. Stat. Soc., vol. 1xxxii., 1919, p. 343. 
(12) BENNETT, T. L/, ¢‘ The Theory of Measurement of Changes in the Cost 
of Living,” Jour. Roy. Stat. Soc., vol. Ixxxiii., 1920, p. 455. 
(18) Frux, A. W., “The Measurement of Price Changes,” Jour. Roy. Stat. 
Sve., vol. \lxxziv., 1821 tp. 167. 
(14) FisHER, IRVING, ‘The Best Form of Index-number,” Quart. Pub. 
Amer. Stat. Ass., March 1921, p. 533. 
(15) Persons, W. M., “Fisher’s Formula for Index-numbers,” Rev. Econ. 
Statistics, vol, iii., 1921, p. 108. 
(16) MArcH, L., ‘Les modes de mesure du mouvement général des prix,” 
Metron, vol. i., No. 4, 1921, p. 40. 
7~ (17) F1sHER, IRVING, The Making of Index-numbers, Houghton Mifflin Co., 
Boston and New York, 1922. (Usefui as a repertory of formule, with 
tests of the results given on certain American data; otherwise, cf. 
reviews in Fconomic Journal, vol. xxxiii., p. 90 and p. 246, and 
Jour. Roy. Stat. Soc., vol. lxxxvi., p. 424.) 
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